A slow-release technique for inducing prolonged paralysis by tetrodotoxin.

A technique is described for the slow-release of tetrodotoxin in peripheral nerves using a constriction capillary. The capillary, which was implanted under the epineurium of the sciatic nerve, released tetrodotoxin from a 25 micrometer pore. Nerve block was complete after approximately 20 min and lasted 6--9 days. Replacement of the capillary enabled paralysis of the rat hindlimb to be maintained for periods of 21 days and longer. Studies with radioactively labelled compounds demonstrated that the efflux rate from the capillary was dependent on the size of the pore and the relative molecular mass of the compound.